Portable wireless transceiver controlling transmission power

ABSTRACT

In the portable telephone of the present invention, a transmission power upper limit value (STEPLIM) in accordance with temperature (T) is found (S 1 , S 2 ), whether the transmission power set value (STEPn) of the next slot exceeds the upper limit (STEPLIM) or not is determined (S 3 , S 4 ), and when it does not exceed, a control signal value (Vc) in accordance with the transmission power set value (STEPn) is applied to a variable gain block ( 11, 13 ) (S 5 , S 7 ). When it exceeds the upper limit, a control signal value (Vc) in accordance with the transmission power upper limit value (STEPLIM) is applied to the variable gain block ( 11, 13 ) (S 6 , S 7 ).

TECHNICAL FIELD

The present invention relates to a portable wireless transceiver and,more specifically, to a portable wireless transceiver controllingtransmission power in accordance with an instruction from a basestation.

BACKGROUND ART

Conventionally, transmission power of a portable telephone is controlledat an optimal value up to the maximum transmission power Pmax (forexample 25 dBm) in accordance with the position of the portabletelephone, for example, so as to allow communication with a base stationand not to hinder communication of other portable telephone with thebase station. The amount of control per one slot of the transmissionpower Px is determined to be ±1 dB, ±2 dB, ±3 dB or the like, andaccuracy of the amount of control ΔP is also determined to be 1 dB±0.5dB, 2 dB±1 dB, 3 dB±1.5 dB, or the like.

Control of the transmission power of the portable telephone is realizedby adjusting a control signal value Vc of a variable gain block. Theportable telephone contains a storage unit, and in the storage unit, atable representing relation between transmission power set value Poutand the control signal value Vc when temperature T is 25° C. is stored,as shown in FIG. 7A. For example, assume that an instruction is issuedfrom the base station to increase the transmission power by 1 dB, whenthe control signal value V2 is applied to the variable gain block andtransmission is performed with transmission power set value Pout=23 dBm.In this case, the transmission power set value Pout is set to 24 dBm, byincreasing the control signal value Vc to V1. The threshold power setvalue Ps is set to 24 dBm, and it is inhibited to set the transmissionpower set value Pout to be higher than the threshold power set value Ps.

When T=25° C., the transmission power set value Pout is equal to theactual transmission power Px. When the temperature T increases, however,the actual transmission power Px decreases even when the control signalvalue Vc is kept constant, as shown in FIG. 8. When the temperature Tlowers, the actual transmission power Px increases, even when thecontrol signal value Vc is kept constant. The reason for this is thatthe gain of the transmission system varies dependent on the temperatureT.

In the example shown in FIG. 8, when T=40° C., by correcting the controlsignal value Vc to Vc+α, it is possible to compensate for the decreasein the transmission power Px. Therefore, conventionally, to the controlsignal value Vc read from the storage unit, a correction value a inaccordance with the temperature T=40° C. is added as shown in FIG. 7B,and the corrected control signal value Vc+α is applied to the variablegain block, whereby change in transmission power Px resulting from thechange in temperature is suppressed.

In the conventional method of power control, however, when power control(ΔP=1 dB) based on the instruction from the base station and powercorrection (ΔP′) in accordance with the temperature T are performedsimultaneously (time t1), the power control amount ΔP+ΔP′ mayundesirably exceed the accuracy specification (1 dB±0.5 dB), as shown inFIG. 9.

DISCLOSURE OF THE INVENTION

Therefore, an object of the present invention is to provide a portablewireless transceiver that can prevent the power control amount fromexceeding the accuracy standard. The portable wireless transceiver inaccordance with the present invention includes a receiving unitreceiving a signal from a base station, a transmitting unit transmittinga signal to the base station with transmission power in accordance witha control signal value, a transmission power finding unit finding acontrol signal value that changes stepwise, corresponding to atransmission power request received from the base station through thereceiving unit, a limit value determining unit detecting the state ofthe transmitting unit and determining a limit value for the controlsignal value changing stepwise based on the state, and a power controlunit controlling transmission power of the transmitting unit inaccordance with the control signal value found by the transmission powerfinding unit, and when the control signal value found by thetransmission power finding unit exceeds the limit value of the limitvalue determining unit, the transmission power of the transmitting unitis controlled in accordance with the limit value. Therefore, it is notthat the transmission power of the transmitting unit is corrected inaccordance with the state of the transmitting unit, but that the limitvalue for the control signal value that changes stepwise is corrected.Therefore, unlike the prior art, it is not possible that the inherentpower control and power correction in accordance with the state of thetransmission unit are performed together resulting in a power controlamount exceeding the accuracy specification.

Preferably, the limit value determining unit determines a limit valuefor the control signal that changes stepwise, based on the temperatureof the transmitting unit. Here, it is not that the transmission power ofthe transmitting unit is corrected based on the temperature, but thatthe limit value for the control signal value that changes stepwise iscorrected based on the temperature. Therefore, unlike the prior art, itis not possible that the inherent power control and temperaturecorrection of the transmission power are performed together resulting inthe power control amount exceeding the accuracy specification.

Preferably, the limit value determining unit determines the limit valuefor the control signal that changes stepwise, based on the temperatureof the transmitting unit and a temperature-limit value table. Here, thelimit value in accordance with the temperature of the transmitting unitcan readily be determined.

Preferably, the limit value determining unit determines the limit valuefor the control signal value that changes step wise, based on thetemperature of the transmitting unit and an expression representingrelation between the temperature-limit value. Here again, the limitvalue in accordance with the temperature of the transmitting unit canreadily be determined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram representing a configuration of a portabletelephone in accordance with an embodiment of the present invention.

FIGS. 2A and 2B represent tables stored in the storage unit shown inFIG. 1.

FIG. 3 shows the relation between each of control signal value Vc,transmission power Px and temperature T, shown in FIG. 1.

FIG. 4 is a flow chart representing an inner loop control of theportable telephone shown in FIG. 1.

FIG. 5 is a time chart representing a specific example of the inner loopcontrol shown in FIG. 4.

FIG. 6 is a time chart representing another specific example of theinner loop control shown in FIG. 4.

FIGS. 7A and 7B represent tables stored in the storage unit of aconventional portable telephone.

FIG. 8 shows the relation between each of control signal value Vc,transmission power Px and temperature T in the conventional portabletelephone.

FIG. 9 is a time chart representing a problem in the inner loop controlof the portable telephone.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a block diagram representing a main portion of a W-CDMA typeportable telephone in accordance with one embodiment of the presentinvention. Referring to FIG. 1, the portable telephone includes anantenna 1, a duplexer 2, a receiving unit 3, a baseband unit 8 and atransmitting unit 9.

A high frequency signal transmitted from a base station and received byantenna 1 is input through duplexer 2 to receiving unit 3. Duplexer 2prevents the received signal from entering transmitting unit 9, and toprevent a transmission signal from entering receiving unit 3. Receivingunit 3 includes a low noise amplifier 4, a mixer 5, a variable gainblock 6 and a quadrature demodulator 7.

The high frequency signal input to receiving unit 3 is amplified by lownoise amplifier 4, and applied to mixer 5. Mixer 5 mixes the input highfrequency signal and an output signal of a local oscillator (not shown),and generates an IF signal. The IF signal is adjusted by variable gainblock 6 to a prescribed power, and applied to quadrature demodulator 7.A control signal value Vc6 of variable gain block 6 is generated bybaseband unit 8.

Quadrature demodulator 7 demodulates the IF signal to generate abaseband signal, which signal is applied to base band unit 8. The baseband signal is demodulated at base band unit 8, converted to a digitalsignal and subjected to a prescribed processing, and converted, forexample, to a voice signal.

On the contrary, a voice signal or the like is subjected to a prescribedprocessing and converted to a digital signal, the digital signal ismodulated by baseband unit 8 to be converted to a baseband signal, andthe baseband signal is input to transmitting unit 9. Transmitting unit 9includes a quadrature modulator 10, variable gain blocks 11, 13, a mixer12, a high power amplifier 14, a gain control unit 15, a storage unit 16and a temperature detecting unit 17.

The baseband signal input to transmitting unit 9 is modulated byquadrature modulator 10 and converted to an IF signal. The IF signal issubjected to power adjustment at variable gain block 11, and applied tomixer 12. Mixer 12 mixes the input IF signal and an output signal of alocal oscillator (not shown), to generate a high frequency signal. Thehigh frequency signal is subjected to power adjustment at variable gainblock 13, amplified by high power amplifier 14, and transmitted to thebase station through duplexer 2 and antenna 1. Temperature detectingunit 17 detects the temperature T of transmitting unit 9, and appliesthe detected value to gain control unit 15.

Storage unit 16 stores a table A representing relation between stepvalue STEP and a control signal value Vc when the temperature D is 25°C., as shown in FIG. 2A. In table A, control signal values Vc=V0, V1,V2, . . . are determined for respective step values STEP=0, 1, 2, . . .. Control signal values Vc=V0, V1, V2, . . . correspond to transmissionpower set values Pout=27, 26, 25, . . . (dBm), respectively.Specifically, when the step value STEP is incremented one by one, thetransmission power set value Pout decrements 1 dB by 1 dB.

In storage unit 16, a table B representing relation between temperatureT (° C.) and upper limit value STEPLIM of the step values STEP isstored, as shown in FIG. 2B. FIG. 2B shows that when temperature Tincreases through −20, 0, 20, 40, 60 (° C.), STEPLIM increases through5, 4, 3, 2, 1. It is inhibited that the step value STEP is made smallerthan the upper limit value STEPLIM.

As shown in FIG. 3, it is assumed that when T=25° C., the transmissionpower set value Pout is equal to the actual transmission power Px, whenT>25° C., Pout<Px, and when T<25° C., Pout>Px. Further, it is assumedthat when T=40° C. and control signal value Vc is set to V2, the actualtransmission power Px attains to the threshold power Plim, and when T=0°C. and Vc=V4, Px=Plim.

Returning to FIG. 1, gain control unit 15 finds the control signal Vcbased on the power control signal Pc from base band unit 8, temperaturedetection value T from temperature detecting unit 17, and tables A and Bstored in the storage unit 16, and applies the control signal value Vcto variable gain blocks 11 and 13 for controlling transmission power.

The method of transmission power control of the portable telephone willbe described in the following. For communication with the base station,first, open loop control is performed. Specifically, base band unit 8generates a control signal value Vc6 of variable gain block 6 so that abase band signal of a prescribed power will be input, calculates thereceived power from the base station based on the control signal valueVc6, and further based on the received power, calculates necessarytransmission power. The smaller the received power, the larger thenecessary transmission power. The larger the received power, the smallerthe necessary transmission power. The transmission power is set to aminimum necessary power, so as not to hinder communication of otherportable telephone. The maximum range of transmission power isdetermined to be 24 dBm−3 dB to 24 dBm+1 dB.

Base band unit 8 applies a power control signal Pc representing thecalculated transmission power, to gain control unit 15. Gain controlunit 15 reads the control signal value Vc which corresponds to thesignal Pc from storage unit 16, and applies the control signal value Vcof the corresponding value to variable gain blocks 11, 13. Base bandunit 8 waits for a reception acknowledge signal returned from the basestation, and when the reception acknowledge signal is not returned,gradually increases the transmission power by a prescribed power at onetime, until the acknowledge signal is received. When the receptionacknowledge signal is returned from the base station, the open loopcontrol ends, and inner loop control is performed.

In the inner loop control, increase/decrease of the transmission poweris instructed from the base station to the portable telephone. This isto correct transmission power when the state of communication changesbecause of movement of the user of the portable telephone, for example.The amount of control of the transmission power includes three types,that is, ±1 dB, ±2 dB and ±3 dB. The accuracy standard of the controlamount is determined to be 1 dB±0.5 dB, 2 dB±1 dB and 3 dB±1.5 dB.Further, DTX control is also known, in which transmission power isdecreased by several dB, when voice is lost during voice communication.At the time of inner loop control, the power control signal Pc appliedfrom the base band unit 8 to gain control unit 15 serves as a signalthat represents the amount of increase/decrease of the transmissionpower.

FIG. 4 is a flow chart representing the inner loop control of theportable telephone shown in FIGS. 1 to 3. In FIG. 4, gain control unit15 detects the temperature T of transmission unit 9 through temperaturedetecting unit 17 in step S1, and reads the step upper limit STEPLIMcorresponding to the temperature T from table B of storage unit 16 instep S2.

Thereafter, in step S3, gain control unit 15 finds the step value STEPnof the next slot based on the power control signal Pc from base bandunit 8, and in step S4, whether the step value STEPn of the next slot islarger than the upper limit value STEPLIM or not is determined.

Thereafter, when it is determined in step S4 that the step value STEPnis larger than the upper limit value STEPLIM, it means that thetransmission power Px of the next slot does not exceed the thresholdpower Plim, and therefore gain control unit 15 sets, in step S5, thestep value STEPn for the next slot to be the step value STEPn found instep S3. When it is determined in step S4 that the step value STEPn isnot larger than the upper limit value STEPLIM, gain control unit 15 setsthe step value STEPn for the next slot to be the upper limit valueSTEPLIM in step S6, so that the transmission power Px of the next slotdoes not exceed the threshold power Plim. Thereafter, in step S7, gaincontrol unit 15 reads the control signal value Vc corresponding to theset step value STEPn from table A of storage unit 16, and applies thecontrol signal value Vc to variable gain blocks 11, 13.

Thereafter, gain control unit 15 determines whether a predeterminednumber N of slots have passed or not in step S8, and when N slots havepassed, the flow returns to step S1, and when N slots have not yetpassed, the flow returns to step S3. This operation is based on theunderstanding that the temperature T of transmission unit 9 does notabruptly change, and therefore, detection of temperature T once in everyN slots is sufficient.

FIG. 5 is a time chart specifically representing the inner loop controlshown in FIG. 4. When the portable telephone is used in the environmentof T=25° C., the step upper limit value STEPLIM is set to 3. When it isinstructed from the base station to increase the transmission power 1 dBby 1 dB, the control signal value Vc is increased stepwise to Vc=V3.When Vc=V3, the transmission power set value Pout attains to thethreshold power Plim=24 dBm. It is noted that when T=25° C., Pout=Px.

When the portable telephone is to be used in the environment of T=40°C., the gain of transmitting unit 9 lowers so that transmission power Pxlowers to 23 dBm, even when the control signal value Vc is kept at V3.The step upper limit value STEPLIM, however, is corrected to 2, andtherefore, when it is instructed from the base station to increase thetransmission power by 1 dB, the control signal value Vc is increased byone step to V2. Consequently, transmission power Px attains to 24 dBm.It is noted that when T=40° C., Pout=Px−1.

FIG. 6 is another time chart specifically representing the inner loopcontrol shown in FIG. 4. FIG. 6 shows an example in which the portabletelephone is moved from the environment where T=25° C. to where T=0° C.When the portable telephone is moved from the environment of T=25° C. toT=0° C., the gain of transmitting unit 9 increases and transmissionpower Px increases gradually, even when control signal value Vc is keptat V3. The step upper limit STEPLIM, however, is corrected to 4, andtherefore, in steps S3, S4 and S6 of FIG. 4, control signal value Vc isset to V4, and the transmission power Px is maintained to be not higherthan the threshold power Plim. It is noted that when T=0° C., Pout=Px+1.

In the present embodiment, when the temperature T changes, not thecontrol signal value Vc but the upper limit value thereof is corrected.Therefore, unlike the prior art, it is possible to prevent the inherentpower control and correction of the control signal value Vc from beingperformed together to cause the power control amount ΔP to exceedaccuracy specification of the inner loop control.

In the present embodiment, table A representing the relation betweenstep value STEP and the control signal value Vc is stored in storageunit 16, and the control signal value Vc corresponding to the step valueSTEPn for the next slot is read from table A. Alternatively, a functionequation representing the relation between the step value STEP and acontrol signal value Vc may be stored in storage unit 16, and gaincontrol unit 15 may calculate the control signal value based on the stepvalue STEPn of the next slot and the function equation.

In the present embodiment, table B representing relation between thetemperature T and a step upper limit value STEPLIM is stored in thestorage unit 16, and the step upper limit value STEPLIM in accordancewith the detected temperature T is read from table B. Alternatively, afunction equation representing the relation between the temperature Tand the step upper limit value STEPLIM may be stored in the storage unit16, and the gain control unit 15 may calculate the step upper limitvalue STEPLIM based on the detected temperature T and a functionequation.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

1. A portable wireless transceiver, comprising: a receiving unitreceiving a signal from a base station; a transmitting unit transmittinga signal to said base station with a transmission power in accordancewith a control signal value; a transmission power finding unit findingthe control signal value that changes stepwise, corresponding to atransmission power request received from said base station through saidreceiving unit, by accessing a first table storing a relation betweenstep values and control signal values for corresponding transmissionpower set values; a limit value determining unit detecting a state ofsaid transmitting unit and determining a limit value for said controlsignal value that changes stepwise based on the detected state; and apower control unit controlling the transmission power of saidtransmitting unit in accordance with the control signal value found bysaid transmission power finding unit, and when the control signal valuefound by said transmission power finding unit exceeds the limit value ofsaid limit value determining unit, controlling the transmission power ofsaid transmitting unit in accordance with said limit value to not exceedsaid limit value.
 2. The portable wireless transceiver according toclaim 1, wherein said limit value determining unit determines the limitvalue for said control signal value that changes stepwise, based ontemperature of said transmitting unit.
 3. The portable wirelesstransceiver according to claim 2, wherein said limit value determiningunit determines the limit value for said control signal value thatchanges stepwise, based on the temperature of said transmitting unit anda temperature-limit value table.
 4. The portable wireless transceiveraccording to claim 2, wherein said limit value determining unitdetermines the limit value for said control signal value that changesstepwise, based on the temperature of said transmitting unit and atemperature-limit relation expression.
 5. A portable wirelesstransceiver, comprising: a receiving unit receiving a signal from a basestation; a transmitting unit transmitting a signal to said base stationwith a transmission power in accordance with a control signal value; atransmission power finding unit finding the control signal value thatchanges stepwise, corresponding to a transmission power request receivedfrom said base station through said receiving unit, by accessing a firsttable storing a relation between step values and control signal valuesfor corresponding transmission power set values; a limit valuedetermining unit detecting a state of said transmitting unit anddetermining a limit value for said control signal value that changesstepwise based on the detected state, by accessing a second tablestoring for different temperature values upper limits of the stepvalues; and a power control unit controlling the transmission power ofsaid transmitting unit in accordance with the control signal value foundby said transmission power finding unit, and when the control signalvalue found by said transmission power finding unit exceeds the limitvalue of said limit value determining unit, controlling the transmissionpower of said transmitting unit in accordance with said limit value tonot exceed said limit value.
 6. The portable wireless transceiveraccording to claim 5, wherein said limit value determining unitdetermines the limit value for said control signal value that changesstepwise, based on temperature of said transmitting unit.